bbundy

I’m thinking about having my valves coated with a Ceramic thermal barrier. Cost about $7.50 a valve to do.

The piston tops are coated now.

Anybody have any experience with having ceramic coatings on combustion chamber stuff?

Bob

neogenesis2004

iTrader: (12)

I've had CC and exhaust ports coated. If you are using stock valves it is possible that the coating will stick to the valve faces. However aftermarket valves, I had Supertech, it might not. The coating would not adhere to the nitride coating bonded to the surface.

bbundy

Good to know. Yes they are aftermarket valves and nitrided. wonder if the nitriding could be sanded off the face first?

Looks like doing the combustion chambers is about $100 think its worth it?

Bob

Savington

iTrader: (31)

Bob, I assume you're trying to avoid burning another valve? Talk to Supertech about whether they can make you a set of Inconel valves. They make them for other applications in the $25-30/ea range.

neogenesis2004

iTrader: (12)

You burnt up a Supertech valve? Wow...

bbundy

Picure is the is the first time it happened. back side of the valve looked like a blow torch was used on it.

Second time it happened after compleat engine rebuild rewired entire car new injectors and compleatly different engine management tuned by FM then double checked at another tuner. It burned the other exhaust valve in the same cylinder after it started consuming oil.

Bob

y8s

iTrader: (8)

was that from retarded timing or what?

leatherface24

iTrader: (10)

wow i cant say ive even seen a more cleaner burnt through valve. +2 on how that happened

bbundy

Ive been running the exact same timing and the same fuel map adjusted down to compensate for less displacement on a stock motor for most of the year after the second time this has happend. It hasn't started burning oil or an exhaust valve yet.

I would sure like to know what caused this no one knows for sure that I have found. I think it has something to do with excess oil in the combustion chamber. The only way I can find that it could be getting there is past the rings though. It did not have a huge amount of blow by when it did it either both the pan and the valve cover were vented to atmospere and smoke was not blowing out the breather and it was not filling up with oil quickly. Spark plug would be wet with oil after a tool around the neigborhood though and going hard into boost would send oil smoke out the tailpipe just prior to both times it did this.

The two times it happened were with entirely different ecu's, ignition systems, injectors, fule pumps, fuel pressure regulators, entire chassis wireing, etc. I don't think it has anything to do with engine management I think it is a mechanical issue.

It was being pushed to around 360 rwhp and pushed fairly well on the track however.

Bob

gaius49

How are the valve seats? Most of the heat absorbed by the valves is dissipated into the seat, so if there were some reduction in seat to valve contact area it could contribute to burning the valve. Also, it would likely not be a good idea to coat the whole valve since doing so would reduce cooling ability. Would it be possible to port the head to increase the turbulence in the chamber to reduce combustion time and avoid flowing burning charge over the exhaust valve? Is there any chance that the cam timing might be a touch off, leading to early opening?

hustler

iTrader: (6)

There's always copper valve coatings with Beryllium seats:


If you want to go with the ultimate in thermal conductivity, and carcinogens.

TurboTim

iTrader: (9)

Manley will make them too. My guy there said they could use the subaru? inconel forging to make a miata valve.